Rationale: Immunotherapy targeting specific immune-regulatory checkpoints, mainly cytotoxic T-lymphocyte antigen-4 (CTLA-4) and Programmed Death (PD1) or PD ligand 1 (PD-L1) have shown spectacular effects in a broad range of solid malignancies, including melanoma and non-small cell lung cancer (NSCLC). Pembrolizumab, is a monoclonal antibody that blocks the interaction between PD-1 on T-cells with its ligands PD-L1 and PD-L2. Anti-tumor activity with an acceptable side effect profile have been shown in melanoma and NSCLC.